Engine starter gearing



March 9, 1943. T. B. MARTIN ENGINE STARTER GEARING Filed Jan. 22, 1941 2 Sheets-Sheet 1 a 4 H fi U i0 INVENIOR.

BY i ATTORNEZY.

March 1943' T. B. MARTIN ,313,656

ENGINE STARTER GEARING Filed Jan. 22, 1941 2 Sheets-Sheet 2 pletely satisfactory.

Patented Mar. 9, 1943 2,313,656 ENGINE sranraa ammo Thomas B. Martin, Dayton,

Ohio, assignor to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application January .22, 1941, Serial No. 375,487 13 Claims. (Cl. 74-7) The present invention relates to engine starter gearing and more automatically connecting a starting motor with a member of an engine to be started, and breaking said connection when the engine becomes self-operative.

In starting gearing of the conventional type which automatically connects and disconnects the starting motor to the engine member, it sometimes happens that the first few explosions of the engine may disconnect the gear ng but the engine fails to remain self-operative and stops, requiring a reactuation of the starting mechanism. Various methods have been proposed to maintain the starting gearing in mesh after such a false start so that the cranking operation may be resumed as soon as the engine slows down to a speed commensurate with the speed of the starting motor, but in general the prior structures have been subject to the disadvantages of complication and expense, and their operation It is an object of the present invention to provide a novel true starter drive for internal combustion engines which is eficient and reliable in operation while being simple and economical in construction.

It is another object to provide such a device in which the starter pinion is positively held in engagement with the engine gear until the pinion has been accelerated to apredetermined speed of rotation.

It is another object to provide such a device in which the pinion and the traversing means are completely disconnected from the starting motor during the overrunning thereof so as to preclude any tendency to transmit torque from the pinion back to the starting motor.

It is another object to provide such a device in which the driving connection from the starting motor to the engine member is re-established in a positive manner as soon as the rotative speed of the starting motor exceeds that of the starter pinion.

Further objects and advantages will be apparent from the following description taken in connection with the accompanying drawings in which:

Fig. l is a longitudinal section partly in elevation of a starter drive constituting one preferred embodiment of the invention;

Fig. 2 is a section taken substantially on the line 2-2 of Fig. 1;

Fig. 3 is a side elevation partly in section of particularly to a device for.

has not always been com-- brazing, a barrel ing shown in driving the structure illustrated. in Fig. 1, the parts beposition;

Fig. 4 is a, side elevation partly in section of a second preferred embodiment of the invention;

Fig. 5 is an end view from the left in Fig. i;

Fig. 6 is a view similar to Fig. 4 showing the parts in driving position;

Fig. 7 is a view similar to Fig. 4 showing the parts in overrunning position; and

' Fig. 8 is a section taken substantially on the line 8-8 of Fig. 4.

In Fig. 1 of the drawings there is illustrated a power shaft l which may be the extended armature shaft of a starting motor, not illustrated. A driving clutch member 2 is fixedly mounted on the end of the power shaft I as by means of a pin 3 retained by a spring ring a and has rigidly mounted thereon, as by welding or member 5. A screw shaft t is slidably journalled on the power shaft within the barrel 5 and is provided with an enlarged end portion 1 having clutch teeth 8 formed thereon adapted to engage the driving clutch member 2 and be driven thereby.

A pinion 9 is slidably journalled on the power shaft I for movementinto and out of engagement with a member such as a gear in of an engine to be started. A nut I l is rigidly connected to the pinion by means of an inner barrel member l2, and is threaded on the screw shaft 6 whereby relative rotation between the screw shaft and nut causes longitudinal motion of the nut and consequently of the pinion 9.

Yielding means for arresting the longitudinal movement of the pinion and nut assembly in order to define the operative position of the pinion, is provided comprising a cylindrical block l3 of elastically deformable material loosely mounted in the barrel 5 hearing at one end against a flange member I fixed in the interior of the barrel by means of a split lock ring Id. The nut H is provided with a radial flange l6 adapted to engage the elastic block l3 when the pinion has been shifted into mesh with the engine gear whereby the travel of the pinion is yieldingly limited.

the flange I6 01' the nut and adapted to bear groove IS in the interior of the barrel when the pinion is in operative position as illustrated in Fig. 3.

Means for insuring initial rotation of the screw shaft 5 with the power shaft l is provided in the form of an elastic friction ring 2| which is anchored in the enlarged end I of the screw shaft as indicated at 22. As will be seen by an examination of Fig. 2, the friction ring 2| is arranged to automatically expand into gripping engagement with a bushing 23, flxedly mounted in any suitable manner in the interior of the barrel 5, when the barrel is rotated in the direction to cause traversal of the pinion into engagement with the engine gear. When the pinion overruns the barrel, however, the friction ring 2| will wrap down on the portion 1 of the screw shaft and slip freely.

Means are provided for establishing a fric-' tional connection between the screw shaft and the power shaft when the screw shaft is overrunning above a predetermined speed, in the form of a spring ring 24 anchored in the enlarged part 1 of the screw shaft as indicated at 25 and wound around said enlarged part in the opposite direction to the ring 2|. Friction ring 24 normally rests in a groove 25 in said portion out of contact with the bushing 23. When the screw shaft is rotated above a predetermined speed, however, the ring 24 moves outward by centrifugal force and engages said bushing to provide the frictional connection stated in order to insure the return of the pinion and barrel assembly to idle position.

In the operation of this embodiment of the invention, starting with the parts in the positions illustrated in Fig. 1, actuation of the power shaft l causes rotation of the clutch member 2 and barrel 5, which rotation is transmitted frictionally to the screw shaft through the spring ring 2|. Rotation of the screw shaft causes traversal of the pinion and nut assembly to the left, engaging the pinion 9 with the engine gear until the flange l5 of the nut is arrested by engagement with the elastic block l3. Screw shaft 6 is thereupon caused to move to the right until the clutch teeth 8 thereon engage the clutch member 2 whereupon the screw shaft is posi-' tiveiy rotated by said clutch member to transmit cranking torque through the pinion to the engine gear, which cranking torque is cushioned by the elastic block 13..

When the engine becomes self-operative, the acceleration of the pinion by the engine gear l8 causes the screw shaft to be declutched from the clutch member 2, backward motion of the pinion and nut assembly being resisted by the detent ILwhich at that time is engaged in the groove IS in the interior of the: barrel 5. If the engine should not remain self-operative, the consequent deceleration of the engine gear permits the power shaft l as rotated by the starting motor to catch up with the pinion 3 and resume driving said pinion to crank the engine until a true start is secured. When the engine is continuously self-operative, the consequent high speed of rotation of the pinion and nut assembly causesthe screw shaft 5 to be rotated thereby at a speed sufficient to engage the spring ring 24 with the bushing 23. The ring 24 thereupon grips the interior of said bushing, causing deceleration of the screw shaft 8 and consequent retraction of the pinion and nut assembly to idle position where it is retained by engagement of the detent inthe groove N3 of the barrel.

In the embodiment of the invention illustrated in Figs. 4 'to 8, a power shaft 3| has fixedly mounttraversing an enlarged driving head 34 on the sleeve and retained by a spring lock ring 35. The driving head 34 is formed with a double-D section as illustrated in Fig. 5 and has non-rotat- 5 ably mounted thereon a barrel 36 which is also 1 manner and having lugs 39 extending into slots 4| of the barrel to spline the flange to the barrel. A cylindrical block 42 of elastically deformable material is loosely mounted in the barrel 36 and engages the flange 38 to yieldingly resist telescop- 5 ing movement of the clutch member 31 into the barrel. Means are provided for preventing the flange member 38 from coming out of the barrel in the form of a lock ring 43 mounted in a groove -.44 in the sleeve 32 and engaging in an elongated circumferential recess 45 in the interior of the clutch member 31.

A stop member in the form of a nut 46 is fixedly mounted on the end of the sleeve 32, and a screw shaft 41 is slidably journalled on said sleeve adjacent said stop and provided with clutch teeth 48 adapted to engage similar clutch teeth I 49 formed on the clutch member 31. Means for frictionally transmitting torque from the sleeve to the screw shaft to initiate rotation of the screw shaft, may be provided if deemed desirable.

As here shown, such means is in the form of a spring detent 50 anchored in the screw shaft and arranged to grip the sleeve 32 upon forward rotation thereof.

5 A pinion 5| is slidably journalled on the power shaft 3| for movement into and out of engagement with an engine gear 52, and has a barrel 53 fixedly mounted thereon in any suitable manner and surrounding the screw shaft and stop memher. A nut 54 threaded on the screw shaft 41 has radial lugs 55 extending into slots 56 in the barrel 53 and retained therein by a lock ring 51 whereby said nut is rigidly connected to the barrel and pinion. Means for normally holding the pinion and nut assembly in idle position is provided in the form of an anti-drift spring 58 interposedbetween the nut 54 and stop member 46.

According to the present invention, means are provided for holding the pinion 5| in engagement with the engine gear 52 until the pinion is rotating above a predetermined speed. As here illustrated, this means is in the form of one or more latch members 59 mounted to slide radially in the barrel 53 and normally held by springs 6| in position to engage a radial flange 62 on the stop.

member 45 as illustrated in Figs. 6 and 7.

In the operation of this embodiment of the invention, rotation of the power shaft 3| by the starting motor is transmitted through sleeve 32,

barrel 35 and elastic block 42 to the clutchmember 31. Rotation is also transmitted frictionally and by means of spring ring 50 from the sleeve 32 to the screw shaft 41 which consequently 05 moves to the left to engage its teeth 48 with the teeth 49 of the clutch member. The screw shaft is then positively rotated by the clutch member, causing traversal of the nut and pinion assembly to the right until the nut engages the stop 43, at

which time the pinion is in engagement with the engine gear as illustrated in Fig. 6. The screw shaft and clutch assembly then moves to the left, compressing the elastic block 42 until the resistance of the engine to rotation is overcome and the ed thereon a sleeve 32 as by means of a pin 33 75, engine is cranked. When the engine starts, the

consequent acceleration of the pinion and nut assembly causes the latches 59 to move out by centrifugal force against the action of the spring 6|, thus permitting the pinion to be drawn back to its inoperative position by the traversing action of the nut 54 on the screw sham 4'! assisted by the anti-drift spring 58.-

Although but two embodiments of the invention have been shown and described in detail, it will be understood that other embodiments are possible and various changes may be made in the de-' sign and arrangement of the parts without departing from the spirit of the invention as defined in the claims appended hereto.

What is claimed is:

1. In an engine starter drive, a power shaft,

a stop member fixed thereon, a pinion slidably journalled on the power shaft and adapted to engage and drive an engine gear, a screw shaft slidably mounted on the power shaft adjacent the stop and freely rotatable thereon, a coupling member mounted on the power shaft adiacent the screw shaft and adapted to be clutched to the screw shaft, means for connecting the coupling member to rotate with the power shaft, and a nut threaded on the screw shaft, means rigidly connecting the nut to the pinion and arranged on rotation of the screw shaft to move the pinion into engagement with the engine gear, which position of the pinion is defined by the engagement of the nut with the stop member, said screw shaft being clutched to the coupling member by the screw jack action of the nut and overrunning said coupling member freely when the engine becomes self-operative while the pinion remains in engagement with the engine gear.

2. In an engine starter drive, a pinion, means for moving the pinion into engagement with an engine gear including a screw shaft and a nut thereon, means rigidly connecting the nut to the pinion, means including an overrunning clutch connection for rotating the screw shaft, and means for holding the pinion in engagement If the engine does not rewith the engine member until the pinion is rotated at a predetermined speed.

3. In an engine starter drive, a pinion, means for moving the pinion into engagement with an engine gear including a screw shaft and a nut thereon, means rigidly connecting the nut to the pinion, a fixed stop for the nut defining the operative position of the pinion, and means including a clutch for rotating the screw shaft, said clutch being closed by movement of the screw shaft away from the stop and constituting the sole driving connection to the screw shaft.

4. An enginestarter drive as set forth in claim 3 in which means are provided for holding the pinion in engagement with the engine member, said holding means being released by rotation of the pinion above a predetermined speed.

5. In an engine starter drive, a pinion, means for moving the pinion into engagement with an engine gear including a screw shaft and a nut thereon, means rigidly connecting thelnut to the pinion, a fixed stop for the nut defining the operative position of the pinion, a driving clutch member having a clutch surface adapted to engage a cranking clutch surface on the adjacent end of the screw shaft, means resisting'longitudinalmovement of the clutch member, and means for returning the pinion to idle position when it is rotated by the engine gear above a predetermined speed.

6. In an engine starter, a powershaft, a driving clutch member non-rotatably mounted thereon, a screw shaft slidably and rotatabLv mounted on the power shaft having a driven clutch surface at one end, a pinion rotatably mounted on the power shaft and slidable thereon into and out of operative position, a nut on the screw shaft, means rigidly connecting the nut to the pinion, a stop limiting movement of the nut away from the driving clutch member, and a centrifugal latch holding the pinion in operative position.

7. In an engine starter, a power shaft, a driving clutch member fixed thereon, a screw shaft having a driven clutch member formed thereon at one end slidably journalled on the power shaft, a pinion slidably journalled on the power Y shaft, a nut threaded on the screw shaft, means rigidly connecting the nut to the pinion, a stop for the nut fixed on the power shaft, and means for cushioning the application of pressure-to the clutch members by the screw jack action of the screw shaft and nut.

8. In an engine starter, a power shaft, a driving clutch member fixed thereon. a screw shaft having a driven clutch member formed thereon at one end slidably Journalled on the power shaft, a pinion slidably Journalled on the power shaft, a nut threaded on the screw shaft, means rigidly connecting the nut to the pinion, a barrel member fixed to the driving clutch member and surrounding the screw shaft and nut, and a stop for the nut in the barrel definingthe operative position of the pinion.

9. In an engine starter, a power shaft, a driving clutch member fixed thereon, a screw shaft having a driven clutch'member formed thereon at one end slidably journalled on the power shaft, a pinion slidably journalled on the power shaft, a nut threaded on the screw shaft, means rigidly connecting the nut to the pinion, a barrel member fixed to the driving clutch member and surrounding the screw shaft'and nut, a yielding stop for the nut in'the barrel, and a frictional driving connection betweenthe barrel and screw shaft.

10. In an engine starter drive a screw shaft.

comprising a driven clutch member, a nut threada barrel connecting the nut and pinion, means limiting lonitudinal movement of the nut, means for rotating the screw shaft including a driving clutch member and means opposing longitudinal movement of the driving clutch member, said clutch members being engaged and disengaged by iongitudinal movement of the screw shaft by the screw-jack action of the screw shaft and nut.

11. In an engine starter drive a screw shaft comprising a driven clutch member, a nut threaded on the screw shaft, a pinion, a barrel connecting the nut and pinion, means limiting longitudinal movement of the nut in the barrel, a detent to hold the nut against said limiting means, means for rotating the screw Shaffi'hb cluding a driving clutch member and means opposing longitudinal movement of the driving clutch member, said clutch members being engazed and disengaged by longitudinal movement of the screw shaft, and centrifugal means for overcoming the action of said detent and releasin: the nut. 7

12. In an engine starter drive, a screw shaft, a nut threaded thereon, a pinion, a barrel connecting the nut and pinion, a fixed stop for the nut. yielding driving means for the screw shaft including a clutch controlled by longitudinal movement of the screw shaft, and yielding frictional means for insuring closure of the clutch upon rotation of the driving means.

13. In an engine starter drive, a power shaft, a pinion slidably iournalled thereon for movespeed,

ment into and out of engagement with an engine gear, a yielding driving connection for the pinion including a screw shaft slidably journalled on the power shaft, and a nut threaded thereon, means rigidly connecting the nut to the pinion, a clutch member fixed to the power shaft, said screw shaft having a clutch surface adapted to cooperate therewith, frictional means adapted to transmit torque from the power shaft to the screw shaft to initiate the rotation of the screw shaft but to slip freely on overrun, and means actuated by centrifugal force for establishing a frictional connection between said shafts when the screw shaft is rotated above a predetermined moms B. 

